Artificial limb and valve therefor



Dec. 12, 1950 o. SHARP l-:rAL

ARTIFICIAL LIMB AND VALVE THEREFOR w vas@ Pressa/'e Vacuum C Patented Dec. 12, 1950 UNITED STATES TENT OFFICE ARTIFICIAL LIME AND VALVE THEREFR Oscar Sharp and William Bellamy, Chicago, lill., assignors to scar Sharp, Chicago, lll., trustee Application August 13, 1948, Serial No. 44,077

6 Claims.

This invention relates to a new and improved artificial limb and particularly to an artificial leg for use by amputees who have lost a leg above the knee joint.

When such an amputation has taken place, a great deal of difficulty is experienced in fitting an artificial limb in such a manner that the patient can walk and sit naturally and in preventing friction between the stump and the socket into which it fits.

Bulky harnesses are ordinarily employed to hold conventional limbs in place. These harnesses are uncomfortable, especially so in hot weather, and it is often impossible for a patient to assume a comfortable sitting position while wearing such a harness. The end of an amputees stump remains tender or pressure-sensitive for years; consequently, it is essential to construct the stump-receiving socket so the end does not bear directly against the bottom of the socket as this would cause pain each time the body weight were applied to the stump in walking. In conventional artificial limbs, therefore, the stump is supported around its sides so that the socket bottom is never pressed against the end of the stump. That construction is disadvantageous and even painful for many people because when the stump moves downward into the socket as load is applied to it, the skin which has been surgically folded over to cover the end of the stump will be stretched taut; in a sense, therefore, the skin at that location is caused to carry a considerable part of the weight of the patient and in a number of cases has caused the end of the stump to break open, disabling the patient and hospitalizing him for long periods.

A primary object of the present invention, therefore, is to provide an artificial limb having a' pressure chamber beneath the stump end and valve means regulating the pressure in that chamber to a predetermined value so that as the stump is moved down into the socket under the weight of the patients body during Walking, the pressure acts upwardly uniformly over the entire stump area to cushion the same without irritating any local pressure-sensitive area, and at the same time eliminating stretching and possible damage to the end skin, as aforesaid. Furthermore, since the pressure is exerted uniformly over the stump end, it need not be high enough to irritate any such pressure-sensitive areas.

Another object of the present invention is the provision of a stump socket lined with resilient rubber-like material for embracing the side periphery of the stump in an air-tight manner and an adjustable pressure relief valve associated withv a pressure chamber at the bottom of the stump socket so the user can adjust the cushioning pressure to his greatest individual comfort.

Another object is the provision of an artificiall limb which avoids the use of the conventional harness to hold it in place; instead, a resilient rubber-like lining is provided in the socket closely following the contour of the stump to provide an air-tight seal so that when the stump is lifted,v

as in walking, the limb is likewise lifted due to suction created in the socket beneath the stumpmeans being provided to break the suction when it is desired to remove the limb, as on retiring stump, said valve being accurate and sensitivein controlling pressures in the order of maghi-- tude of 20-30 ounces per square inch, being easily cleaned, and having means for quickly removing it to break the vacuum in the socket to permit ready removal of the limb when desired.

Another object is the provision of a stumpreceiving socket so constructed as to permit (when the socket is used in an artificial leg) normal exing of the muscles during walking movement which keeps the stump in a healthy condition instead of shriveling, as is generally the case with conventional sockets which do not permit such normal muscular flexing. Ancillary to this is another object of providing a resilient:

coating on the socket inner wall which, at rest,

makes a substantially air-tight seal with the stump side periphery, and which coacts with the flexing of the muscles during walking to pump a slight amount of air into the chamber beneath the stump at each step to keep said chamber con-l Fig. 2 is an outside view of the valve means'- shown in Fig. 1; .l Fig. 3 is a sectional view of Fig. 2 taken along the line 3-3 showing the working parts of the valve in enlarged section;

Fig. 3a is a further enlarged view of the spring and valve disc elements shown in Fig. 3; and

Fig. 4 is a View similar to Fig. 3 (except that the removable valve member is not shown in cross-section) showing the valve means as it would be partially disassembled to prevent the formation of a vacuum in the stump socket to permit removal of the limb from the stump when desired.

Referring now more particularly to the embodiment shown in the drawings, the artificial limb generally designated 2| comprises stump receiving socket member 22 adapted to receive a stump 23, and a calf member 24 having any suitable type of connecting hinged joint which in this case is generally designated 26. VThe knee joint construction will not be further described for it forms no part of the present invention and any conventional knee joint may be utilized.

As best shown in Figure 3, the socket member 22 is preferably formed of wood, such as wellseasoned willow. The socket 21 will usually be of somewhat irregular shape, preferably conforming as closely as possible to the peripheral surface 28 of the stump and should, therefore, be made up specially for each individual case. For best results, the wood should be completely waterproofed by applying several coats of waterresistant lacquer 29 to all surfaces. To the inner surface 3| is attached, as by cement (not shown) a layer of resilient compressible material 32,

such as felt. The felt will be preferably about 5 1/8" to 1/4" in thickness. On the top of the felt layer will be an overlayer of perspiration-resistant rubber-like material 33, such, for instance as rubber latex, which is preferably sprayed in place to a thickness of about ,1 6 of an inch. The stump-encircling surface 34 of the latex layer will conform as closely as possible to the stump surface 28, and the resilience of the combined felt and latex layers will be suiicient to absorb any variations in the stump surface 28 due to muscular exing.

The socket member 22 will preferably be constructed so that the closed bottom wall 36 is about 11/2" below the end of the stump, as shown in Fig. 1, to thereby define a pressure and vacuum chamber 31 therebetween. As will be seen in the subsequent description, pressure existing in the chamber 31 will be effective to cushion the end of the stump when the latter is loaded during walking.

Valve means generally `designated 38 is provided to regulate the pressure in the chamber 31 when the stump is urged into the socket and to create a partial vacuum therein when the stump is urged away from the socket while the valve is in place.

The details of the valve means are best shown in Figs. 3, 3a and 4, and comprise a fixed mounting member 39 and a removable sealing member 4|.

The mounting member comprises an annular bushing threaded internally at 42 having a ange 43 with an outwardly disposed sealing surface 44 and a knurled or otherwise suitably roughened outside surface 46, to facilitiate cemented mounting in the opening 41 formed in the side wall of the socket member. As shown, this opening 41 is provided so the mounting member 39 communicates directly with the pressure and the vacuum ychamber 31.

The removable sealing member 4| is formed with an exterior threaded portion 48 engageable with the interior threads 42 previously described. A flanged portion 49 is provided having a larger diameter than the threaded portion and being spaced axially therefrom. A groove 5i of lesser diameter than the threaded portion is provided between the latter and the flange 49, one surface 52 of the flange defining a wall of the groove. An annular rubber-like gasket 53 is retained in the groove and has an external diameter larger than the threaded portion 48 whereby the surface 54 of the gasket is normally seated against the flange wall 52 and the gasket surface 56 is adapted to be seated against the surface 44 of the fixed valve member.

The removable sealing member 4| is provided with means for gripping it for hand manipulation which in this case comprises a semi-circular bail 51 engaged in diametrically disposed recesses 58 formed in the periphery of the flange 49. As will be seen in Figs. 1 and 4, the bail may be moved to an outward position so that it may be readily grasped by the patients hand and used as a handle for screwing or unscrewing the valve member. As shown in Fig. 2, the bail may be turned to an out-of-the-way position when not in use and in this position it will not interfere with the users clothing and will even permit drawing a stocking up over it if such be desired.

The pressure and suction controlling elements of the valve structure are best shown in Figs. 3 and 3a. As there shown, the sealing member is formed with axially aligned inlet and outlet bores 59 and @i respectively, separated by a bridge wall the latter having a larger diameter. A raised narrow annular seat 62 is formed on the outlet side of the bridge wall. A pressure adjusting screw 63 i5 provided with threads B4 which are engageable with threads 66 formed in the outlet bore of the sealing member and has an L-shaped passage 31 formed therethrough to provide communication between the outlet bore 6| and the surrounding atmosphere. On the forward or inner end of the adjusting screw is an axial extension 58 of reduced diameter and serves as a guide for coil compression spring 69 which closely embraces it. At the forward end of the coil spring 54 is mounted, preferably by a layer of cement 1|, a disc 12 of soft rubber-like material which is engageable With the raised seat 62. As shown in Figs. 2 and 3 a screw slot 13 is formed in the exterior end portion of adjusting screw 63 to facilitate turning it to adjust the compression of the spring. In use the patients stump will be pressed into the socket 21 into substantially airtight, pressure-sealing engagement with the latex overlayer 33. As the stump is pressed into the socket the excess air will be relieved, past the valve disc 12, to atmosphere. The stump will then stay in place within the socket member, for any attempt to withdraw the stump will create 4a partial vacuum Within the chamber 31 suiiicient to permit such withdrawing movement. For most applications, with individuals weighing between 100 and 200 pounds, the strength of the spring E3 and the cross-section of the opening of seat 62 will be chosen so that the pressure within the chamber 31 may be maintained at any one of a range of values between 20 and 30 ounces. A heavy person, of course, will find a higher pressure more comfortable than a light person. Some experimentation will be required on the part of an individual user to find the most comfortable pressure from time to time.

We have found that in actual use on a number of cases the resilient interlining such as we have described for the socket 21 will cooperate with the stump so that as a result of flexing of the muscles during normal walking there is actually a slight amount of air continually being pumped down the inner wall of the socket into the cham.- ber 3l; on the contrary there is seldom, if ever, any reverse flow when the stump is urged upwardly relative to the socket so there is never any tendency to break the vacuum in the chamber 31 when the articial limb is lifted during walking. When the user has adjusted the screw 63 to the point where it is most comfortable to wear, it is often unnecessary to change the adjustment for several days at a time. however, it will be necessary to make minor adjustments to compensate for diierent temperature and humidity conditions which will make a different cushioning pressure seem more comfortable.

The stump is supported by the socket in two ways: rst, its peripheral surface 2B will be sup ported by the encircling socket surface in a more or less frictional manner; and, second, the cushioning pressure in chamber 3l will support the end of the stump pneumatically. There will usuallybe, for a particular patient, some one depth to which the stump is normally pressed into the socket which will provide him with the optimum of comfort in walking. Now, during hot weather, when there is a greater tendency to perspire, this increased perspiration from the stump will lubricate the socket wall so that the stump tends to be pressed farther into the socket during walking. Since the cross-section of the stump contracts downwardly, this would cause the entire stump to be contracted unnaturally thereby giving rise tc discomfort. Under such conditions this discom fort can be avoided simply by increasing the compression on spring 89 to thereby increase the cushioning pressure in the chamber 3l' so a greater proportion of the patients weight will be supported by the pressure cushion to keep the stump up in its normal, comfortable position.

In removing the artificial limb, as for instance before retiring in the evening, the patient simply pivots the bail 5l outward to the position of Fig. 4 where it can readily be grasped by his hand and he then rotates the entire sealing member 4I in a counterclockwise direction. He can then slip the artificial limb oil with no difficulty because no vacuum will be formed in chamber 31.

For best results, an articial limb and all parts associated therewith must be cleaned at regular intervals and an important part of the present invention resides in the ease with which the parte of the valve means may be disassembled, cleaned, and reassembled, even by persons who are not mechanically inclined. The entire valve may be disassembled in a few second simply by back-rctating the adjusting screw 63, and this can be done even with a nger nail or a coin engaged in the slot 13, to expose all parts for a thorough cleaning.

Another important feature of the invention resides in the mounting of the valve disc l2. This valve disc must be of very light construction possessing only a minimum inertia so as to be accurately responsive to the low pressure differen tials and low ow rates involved and still close tightly when flow tends to reverse. To achieve this low inertia, the valve disc is cemented onto the end of the spring 64 instead of being attached by any conventional clamping means. The con- From season to season,-

struction also avoids any complicated or involved means for contacting lthe disc 'I2 to guide it into alignment with the seat 62 by the construction which involves mounting the disc on the end of the spring as described above and by closely embracing the guide extension 68 on the end of the adjusting screw. This construction also makes it feasible for non-mechanically inclined patients to readily install a new valve disc sub-assembly when needed. Another advantage of the construction is that the gasket 53 is seated in groove 5I so that it can never be inadvertentlydropped from the sealing member, but on the other hand, when necessary, it may readily be replaced merely by stripping it oi and placing a new one in the groove.

While a particular form of the present invention has been shown, it will be apparent that minor changes therein will readily suggest themselves to others skilled in the art without departing from the spirit and..scope of the invention. Furthermore, while the invention has been specically illustrated in connection with an articial limb for an above-the-knee amputee, it will be apparent that the invention may be advantageously applied to limbs for below-the-knee amputations, as well as to artificial arms.

We claim:

1. An articial limb including a socket member adapted to receive the stump of a patients limb, said socket member being formed with an encircling side wall adapted to follow the contour of the stump and having a bottom portion adapted to be spaced from the stump to define a pressure chamber beneath the stump, said socket side wall having a resilient rubber coating adapted to contact the sides of the stump to partially support the same when the stump is pressed into the socket and to provide a substantially airtight engagement therewith, said socket member having valve means disposed to control communication between said chamber and the outside atmosphere and being effective to maintain a predetermined air pressure in said chamber to cushionably support the stump; whereby, when load is applied to press the stump into the socket the stump is supported by said predetermined air pressures acting uniformly over the bottom of the stump in addition to the support aiTorded by the socket side wall itself.

2. An artificial limb according to claim 1 in which said resilient coating comprises an underlayer of felt and an overlayer of rubber bonded thereto.

3. An articial limb including a socket member adapted to receive the stump of a patients limb, said socket member being formed with an encircling side wall adapted to follow the contour of the side periphery of the stump and having a bottom portion adapted to be spaced from the stump to dene a pressure and vacuum chamber beneath the end of the stump, said socket having a layer of resilient material and an overlayer of perspiration resistant rubber adapted to contact and support said side periphery of the stump to provide a substantially air-tight engagement therewith; said socket member having relief valve means adapted to relieve pressure in said chamber to atmosphere when the pressure exceeds a Ipredetermined amount and adapted to prevent the ow of air into said chamber to create a suction condition therein when the socket is urged away from the stump to thereby hold the limb in place; means for adjusting said relief valve means to cause it to relieve at any one 0i -a range of Vpredetermined pressures whereby, when load is applied lto press the stump into the socket, the stump is supported by a cushion of said predeterminedair pressure acting uniformly over the end of the stump in addition to the support vprovided by the socket side wall itself; and means for admitting air into said chamber to break vthe suction therein when it is desired to remove `the limb from the stump.

4. An artificial limb including a socket member adapted to receive the stump of a patients limb, said socket member being formed with a socket having an inner wall covered with rubber and adapted `to follow the side contour of the stump and form an air-tight seal therewith, the bottom of said socket being formed to bespaced beyond the end .of the stump to define a pressure chamber, and valve means mounted in the .side wall of ythe Vsocket member including a sealing member threadably Aengaged with a fixed member 4mounted in the socket wall, said sealing Ymember carrying .a gasket adapted to provide an air-tight `ioint with the iixed member when the tivo are threaded together, means .carried by said sealing member and extensible suiciently beyond `the wall of the socket member to provide a grip for manually assembling and disassembling the sealing member relative to said wall :to Vregulate the vacuum in said chamber, and pressure relief valve means in said sealing member effective to maintain a predetermined cushioning pressure in the chamber beneath the stump when the latter is pressed into the socket.

5. An artificial limb including a socket member adapted to receive the stump of a patients limb, said socket member being formed with a socket having an inner wall covered with a coating of resilient rubber-like material and adapted to encircle in a substantially air-tight manner `the periphery of the stump, the bottom of said socket being formed to be spaced beyond the end of the stump to dene a chamber therebetween, said resilient rubber-like coating conforming to the peripheral surface of the stump and cooperating ierewith whereby flexing of the stump muscles coincident with reciprocal movement of the stump within the socket is effective to pump air down past the stump into said chamber and whereby reverse air flow from the chamber upward past the stump is substantially prevented; s?,

pressure relief valve means in said socket wall for relieving air pressure in said chamber at a predetermined maximum value to maintain said predetermined pressure in said chamber during `slight relative movement between the stump and ciated with said relief valve means for adjustably varying said predetermined maximum pressure within the chamber to the patients optimum comfort; means associated with said valve means for preventing ow of air therethrough into said chamber when the stump is urged outwardly from said socket to create a partial vacuum in said chamber to maintain the limb in place on the stump; and vmanually manipulatable means for removing the valve means from the socket wall for breaking the vacuum in said chamber when desired to permit the ready removal of the limb from .the stump.

6. An artificial limb including a socket member adapted to receive the stump of a patients limb, said socket member being formed with a socket having .an inner wall covered with a layer of resilient, stump-conforming rubberlike material adapted to lend itself flexibly to the side contour of the stump and form an air-tight seal therewith, the bottom of said socket being formed to be spaced beyond the end of the stump to define a pressureand vacuum chamber, said socket having a port in the sidewall thereof providing communication between said pressure and Vacuum chamber and the exterior atmosphere, valve means threadably mounted in said port for controlling the passage of air through said port, and manually manipulatable means carried by said valve means being extensible sufliciently beyond the wall of the socket member to provide a grip for manually threading the valve means into and out of the socket member to thereby make and break the seal in said pressure and vacuum chamber to facilitate applying the limb to and removing it from the stump.

OSCAR SHARP. WILLIAM BELLAMY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 794,147 Farris July 4, 1905 1,868,303 Balch et al July 19, 1932 2,359,008 ASmith Sept. 26, 1944 FOREIGN PATENTS Number Country Date 605,534 Germany Nov. 13, 1934 650,858 Germany Oct. 2, 1937 OTHER REFERENCES Research Reports on Artificial Limbs by Committee on Artificial Limbs, National Research f, Council. A copy was recd. in Div. on Nov. 13,

1947. vPages 27, 74, 75, 92. 93 and 94.

Memo to Limbmakers on the Suction Socket Program, by Committee on Articial Limbs, National Research Council, Nov. 8, 1946. Tests of retention of knurled, grooved and smooth valve rings in wood sockets. 

